java - LazyInitializationException 尽管有 OpenSessionInViewFilter

Question

尽管在堆栈跟踪本身中看到过滤器，但我似乎在 Spring/MVC 3.0/Hibernate 3.5 应用程序中随机获得以下 LazyInitializationException。关于我应该研究什么有什么想法吗？

07 Jun 2011 13:48:47,152 [ERROR]  (http-3443-2) org.hibernate.LazyInitializationException: could not initialize proxy - no Session
org.hibernate.LazyInitializationException: could not initialize proxy - no Session
    at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:86)
    at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:140)
    at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:190)
    at com.test.Image_$$_javassist_18.getMyKey(Image_$$_javassist_18.java)
    at com.test.AppTagHelper.getAssetUrl(AppTagHelper.java:66)
    at sun.reflect.GeneratedMethodAccessor81.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.el.parser.AstFunction.getValue(AstFunction.java:110)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
    at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:935)
    at org.apache.jsp.WEB_002dINF.view.home_jsp._jspx_meth_c_005fout_005f2(home_jsp.java:1027)
    at org.apache.jsp.WEB_002dINF.view.home_jsp._jspx_meth_c_005fwhen_005f1(home_jsp.java:1002)
    at org.apache.jsp.WEB_002dINF.view.home_jsp._jspx_meth_c_005fchoose_005f1(home_jsp.java:969)
    at org.apache.jsp.WEB_002dINF.view.home_jsp._jspx_meth_display_005fcolumn_005f0(home_jsp.java:867)
    at org.apache.jsp.WEB_002dINF.view.home_jsp._jspService(home_jsp.java:214)
    <<VARIOUS SPRING FILTERS>>
    at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)

来自 web.xml:

<filter>
    <filter-name>hibernateFilter</filter-name>
    <filter-class>
        org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
    <init-param>
    <param-name>sessionFactoryBeanName</param-name>
        <param-value>sessionFactory</param-value>
    </init-param>
</filter>

<filter-mapping>
    <filter-name>hibernateFilter</filter-name>
    <url-pattern>*.html</url-pattern>
</filter-mapping>
<filter-mapping>
    <filter-name>hibernateFilter</filter-name>
    <url-pattern>*.json</url-pattern>
</filter-mapping>

更新，添加SessionFactoryBean的定义:

<bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean" depends-on="dataSource">
    <property name="dataSource" ref="dataSource" />
    <property name="packagesToScan" value="com.test.model" />
    <property name="schemaUpdate" value="false" />
    <property name="eventListeners">
      <map>
        <!-- Create -->
        <entry key="pre-insert">
          <ref local="hibernateCreateListener"/>
        </entry>
        <entry key="post-insert">
          <ref local="hibernateRevisionListener"/>
        </entry> 
        <!-- Update -->
        <entry key="pre-update">
          <ref local="hibernateUpdateListener"/>
        </entry>
        <entry key="post-update">
          <ref local="hibernateRevisionListener"/>
        </entry>
        <entry key="post-delete">
          <ref local="hibernateRevisionListener"/>
        </entry>
        <entry key="pre-collection-update">
          <ref local="hibernateRevisionListener"/>
        </entry>
        <entry key="post-collection-recreate">
          <ref local="hibernateRevisionListener"/>
        </entry>
        <entry key="pre-collection-remove">
          <ref local="hibernateRevisionListener"/>
        </entry>                   
      </map>
    </property>
    <property name="entityInterceptor">
      <ref bean="hibernateAuditInterceptor"/>
    </property>
    <property name="hibernateProperties">
      <props>
        <prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop>
        <prop key="hibernate.default_schema">${app.databaseSchema}</prop>                 
        <prop key="hibernate.show_sql">false</prop>
        <prop key="hibernate.format_sql">false</prop>
        <prop key="hibernate.use_sql_comments">false</prop>
        <prop key="hibernate.connection.oracle.jdbc.ReadTimeout">60000</prop>
        <prop key="org.hibernate.envers.revisionTypeFieldName">REV_TYPE</prop>
        <prop key="org.hibernate.envers.revisionFieldName">REV_ID</prop>        
      </props>
    </property>
  </bean>

Answer 1

我知道的两个最常见的导致过滤器打开的延迟加载异常的原因是在异常使 Hibernate session 无效后尝试访问某些内容，或者尝试访问某个字段实际上坐在 Web session 中并且没有附加。

public interface EntityService {

  @Transactional
  EntityA getA(Long id);

  @Transactional
  EntityB getB(Long id);
}

public class WebPageController {

  public void handleGet(Long id1, Long id2) {
    EntityA a = entityService.getA(id1);
    try {
      EntityB b = entityService.getB(id2);
    } catch (Exception e) {
      //print somthething
    }
    a.accessLazyField(); //will throw lazy load after getB throws exception
  }
}

显然为了清楚起见省略了很多代码和注释 :)

@SessionAttributes("model")
public class WebPageController {

  @ModelAttribute("model")
  @RequestMapping(method=RequestMethod.GET)
  public EntityA handleGet(Long id) {
    return entityService.getA(id);
  }

  @RequestMapping(method=RequestMethod.POST)
  public String handlePost(@ModelAttribute("model") EntityA a) {
    a.accessLazyField(); //will throw lazy load if the field was not accessed during original page rendering
    return "viewName";
  }
}